I have driven both the 320d and the (European) 325i. Revving up to 7000rpm is so much more fun than the sound of a civilized truck engine.

The 325i is one second slower on 80-120km/h acceleration in fourth gear than the 320d (7.5s vs 6.5s) . I am sure the 325i is quicker when you put it in third gear, which I think is not possible with the 320d (at least not all the way up to 120km/h).